U.S. patent application number 09/924059 was filed with the patent office on 2002-02-21 for liquid crystal display and image display device using the same.
Invention is credited to Matsumoto, Seiichi.
Application Number | 20020021398 09/924059 |
Document ID | / |
Family ID | 18732862 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020021398 |
Kind Code |
A1 |
Matsumoto, Seiichi |
February 21, 2002 |
Liquid crystal display and image display device using the same
Abstract
A liquid crystal display (LCD) is provided which is capable of
reducing wiring resistance at a routing section of a common wiring
and changes in a common voltage to be applied to the common wiring,
thus achieving a reduction in "color degradation" and "horizontal
stroke" in the LCD and of reducing "luminance irregularity". The
liquid crystal display (LCD) has a first routing section made up of
a metal film having very low transmittance of light emitted from a
backlight and formed in a manner that a gap between blocks being
adjacent along one side of a display area is almost filled in and a
second routing section made up of the above metal film and formed
in a manner that a region surrounded by an outer side portion of a
block mounted outside the display area and by straight lines being
four sides of the display area which have extended toward end
portions of a glass substrate is almost filled in.
Inventors: |
Matsumoto, Seiichi; (Tokyo,
JP) |
Correspondence
Address: |
McGinn & Gibb, PLLC
Suite 200
8321 Old Courthouse Road
Vienna
VA
22182-3817
US
|
Family ID: |
18732862 |
Appl. No.: |
09/924059 |
Filed: |
August 8, 2001 |
Current U.S.
Class: |
349/149 |
Current CPC
Class: |
G02F 1/1345 20130101;
G02F 2201/121 20130101 |
Class at
Publication: |
349/149 |
International
Class: |
G02F 001/136 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2000 |
JP |
241714/2000 |
Claims
What is claimed is:
1. A liquid crystal display comprising: a liquid crystal cell
disposed at each point of intersections of a plurality of scanning
lines, extending in a row direction, mounted at specified intervals
in a display area being approximately quadrangular in shape placed
at a predetermined position on a glass substrate being
approximately quadrangular in shape and of a plurality of signal
lines, extending in a column direction, mounted at specified
intervals and containing a common electrode; signal terminals
mounted at either or both of upper end portions or lower end
portions of said glass substrate at a specified pitch, to which end
portions of said signal lines routed to either or both of an upper
portion on an upper side or of a lower portion on a lower side of
said display area and divided into two or more blocks and gathered
are connected; scanning terminals mounted at either or both of left
end portions or right end portions of said glass substrate at a
specified pitch, to which end portions of said scanning lines
routed to either or both of a left portion on a left side or of a
right portion on a right side of said display area and divided into
two or more blocks and gathered are connected; common signal lines
each being mounted in each row and each column in said display area
used to apply a common voltage to said common electrode; common
wirings each being mounted at either or both of an upper portion on
an upper side or of a lower portion on a lower side of said display
area and mounted at either or both of a left portion on a left side
or of a right portion on a right side of said display area, to
which each of end portions of a plurality of said common signal
lines is connected; a first routing section made up of a metal film
having very low transmittance of light emitted from a backlight and
formed in a manner that a gap between blocks being adjacent to each
other along one side of said display area is almost filled in, and
wherein one portion facing said display area of which is connected
to said common wiring; a second routing section made up of said
metal film and formed in a manner that a region surrounded by an
outer side portion of each of said blocks and by straight lines
being four side lines of said display area being extended toward an
end portion of said glass substrate is almost filled in, and
wherein one portion facing said display area of which is connected
to said common wiring; and a plurality of common terminals mounted
so as to be adjacent to said signal terminal or said scanning
terminal connected to an end portion of each of said signal lines
or said scanning lines making up an outermost portion of each of
said blocks and formed on said first routing section and said
second routing section at an end portion of said glass
substrate.
2. The liquid crystal display according to claim 1, wherein said
first routing section and said second routing section formed at
either or both of said left portion on said left side or of said
right portion on said right side of said display area are formed on
a same layer as a plurality of said scanning lines is formed and
connected to said common wiring through a contact hole and wherein
said first section and said second section formed at either or both
of said upper portion on said upper side or of said lower portion
on said lower side of said display area are formed on a same layer
as a plurality of said signal lines is formed and connected to said
common wiring through said contact hole.
3. The liquid crystal display according to claim 1, wherein each of
said common wirings is made up of a longitudinal line and a
horizontal line contacting sides of said display area and wherein
said longitudinal line is formed on a same layer as a plurality of
said signal lines is formed and said horizontal line is formed on a
same layer as a plurality of said scanning lines is formed and said
common wirings are connected to each other at a region where said
longitudinal line and horizontal line are overlapped through
contact holes and wherein each of said common signal lines is
formed on a same layer as each of a plurality of said scanning
lines is formed and connected to said longitudinal line through
contact holes.
4. The liquid crystal display according to claim 1, wherein said
first routing section and said second routing section are formed in
a manner that each of said routing sections is placed far, by an
interval being equal to a predetermined pitch, from said scanning
lines or said signal lines being positioned at outermost portions
of blocks adjacent to each other.
5. A liquid crystal display comprising: a liquid crystal cell
disposed at each point of intersections of a plurality of scanning
lines, extending in a row direction, mounted at specified intervals
in a display area being approximately quadrangular in shape placed
at a predetermined position on a glass substrate being
approximately quadrangular in shape and of a plurality of signal
lines, extending in a column direction, mounted at specified
intervals, and containing a common electrode; signal terminals
mounted at either or both of upper end portions or lower end
portions of said glass substrate at a specified pitch, to which end
portions of said signal lines routed to either or both of an upper
portion on an upper side or of a lower portion on a lower side of
said display area and divided into two or more blocks and gathered
are connected; scanning terminals mounted at either or both of left
end portions or right end portions of said glass substrate at a
specified pitch, to which ends of said scanning lines routed to
either or both of a left portion on a left side or of a right
portion on a right side of said display area and divided into two
or more blocks and gathered are connected; common signal lines each
being mounted in each row and each column in said display area used
to apply a common voltage to said common electrode; common wirings
each being mounted at either or both of an upper portion on an
upper side or of a lower portion on a lower side of said display
area and mounted at either or both of a left portion on a left side
or of a right portion on a right side of said display, to which
each of end portions of a plurality of said common signal lines is
connected; a first routing section made up of a metal film having
very low transmittance of light emitted from a backlight and formed
in a manner that a gap between blocks, being adjacent to each
other, formed in a manner so as to surround said display area, is
almost filled in, and wherein one portion facing said display area
of which is connected to said common wiring; a second routing
section made up of said metal film and formed in a manner that a
region surrounded by an outer side portion of each of said blocks
and by a straight line being one side being orthogonal to one side
of said display area along which said block contacts, being
extended toward an end portion of said glass substrate, is almost
filled in, and wherein one portion facing said display area of
which is connected to said common wiring; and a plurality of common
terminals mounted so as to be adjacent to said signal terminal or
said scanning terminal connected to an end portion of said signal
line or said scanning line making up an outermost portion of each
of said blocks and formed on said first and second routing sections
at an end portion of said glass substrate.
6. The liquid crystal display according to claim 5, wherein said
first routing section facing a corner portion of said display area
is made up of a first approximate trapezoidal portion formed on a
same layer as a plurality of said scanning lines is formed and of a
second approximate trapezoidal portion formed on a same layer as a
plurality of said signal lines is formed, wherein said first
approximate trapezoidal portion is formed in a manner that it
reaches a place being positioned opposite to said scanning line
disposed at an outermost portion of said adjacent blocks where a
straight line connecting an end of each of said signal terminals
mounted at said specified pitch and an end of each of said scanning
terminals on a side of said display area is extended and where said
common wiring is extended, wherein said second approximate
trapezoidal portion is formed in a manner that it reaches a place
being positioned opposite to said signal line disposed at an
outermost portion of said adjacent blocks where a straight line
connecting an end of each of said signal terminals mounted at said
specified pitch and an end of each of said scanning terminals on a
side of said display area is extended and where said common wiring
is extended, and wherein said first approximate trapezoidal and
said second approximate trapezoidal portion are connected to each
other at a portion where they are overlapped through contact holes
with specified numbers and at a specified pitch.
7. The liquid crystal display according to claim 5, wherein each of
said common wirings is made up of a longitudinal line and a
horizontal line contacting sides of said display area and wherein
said longitudinal line is formed on a same layer as a plurality of
said signal lines is formed and said horizontal line is formed on a
same layer as a plurality of said scanning lines is formed and said
common wirings are connected to each other at a region where said
longitudinal line and horizontal line are overlapped through
contact holes and wherein each of said common signal lines is
formed on a same layer as each of a plurality of said scanning
lines is formed and connected to said longitudinal line through
contact holes.
8. The liquid crystal display according to claim 5, wherein said
first routing section and said second routing section are formed in
a manner that each of said routing sections is placed far, by an
interval being equal to a predetermined pitch, from said scanning
lines or said signal lines being positioned at outermost portions
of blocks adjacent to each other.
9. An image display device provided with a liquid crystal display
comprising: a liquid crystal cell disposed at each point of
intersections of a plurality of scanning lines, extending in a row
direction, mounted at specified intervals in a display area being
approximately quadrangular in shape placed at a predetermined
position on a glass substrate being approximately quadrangular in
shape and of a plurality of signal lines, extending in a column
direction, mounted at specified intervals and containing a common
electrode; signal terminals mounted at either or both of upper end
portions or lower end portions of said glass substrate at a
specified pitch, to which end portions of said signal lines routed
to either or both of an upper portion on an upper side or of a
lower portion on a lower side of said display area and divided into
two or more blocks and gathered are connected; scanning terminals
mounted at either or both of left end portions or right end
portions of said glass substrate at a specified pitch, to which end
portions of said scanning lines routed to either or both of a left
portion on a left side or of a right portion on a right side of
said display area and divided into two or more blocks and gathered
are connected; common signal lines each being mounted in each row
and each column in said display area used to apply a common voltage
to said common electrode; common wirings each being mounted at
either or both of an upper portion on an upper side or of a lower
portion on a lower side of said display area and mounted at either
or both of a left portion on a left side or of a right portion on a
right side of said display area, to which each of end portions of a
plurality of said common signal lines is connected; a first routing
section made up of a metal film having very low transmittance of
light emitted from a backlight and formed in a manner that a gap
between blocks being adjacent to each other along one side of said
display area is almost filled in, and wherein one portion facing
said display area of which is connected to said common wiring; a
second routing section made up of said metal film and formed in a
manner that a region surrounded by an outer side portion of each of
said blocks and by straight lines being four side lines of said
display area being extended toward an end portion of said glass
substrate is almost filled in, and wherein one portion facing said
display area of which is connected to said common wiring; and a
plurality of common terminals mounted so as to be adjacent to said
signal terminal or said scanning terminal connected to an end
portion of each of said signal lines or said scanning lines making
up an outermost portion of each of said blocks and formed on said
first routing section and said second routing section at an end
portion of said glass substrate.
10. An image display device provided with a liquid crystal display
comprising a liquid crystal cell disposed at each point of
intersections of a plurality of scanning lines, extending in a row
direction, mounted at specified intervals in a display area being
approximately quadrangular in shape placed at a predetermined
position on a glass substrate being approximately quadrangular in
shape and of a plurality of signal lines, extending in a column
direction, mounted at specified intervals, and containing a common
electrode; signal terminals mounted at either or both of upper end
portions or lower end portions of said glass substrate at a
specified pitch, to which end portions of said signal lines routed
to either or both of an upper portion on an upper side or of a
lower portion on a lower side of said display area and divided into
two or more blocks and gathered are connected; scanning terminals
mounted at either or both of left end portions or right end
portions of said glass substrate at a specified pitch, to which
ends of said scanning lines routed to either or both of a left
portion on a left side or of a right portion on a right side of
said display area and divided into two or more blocks and gathered
are connected; common signal lines each being mounted in each row
and each column in said display area used to apply a common voltage
to said common electrode; common wirings each being mounted at
either or both of an upper portion on an upper side or of a lower
portion on a lower side of said display area and mounted at either
or both of a left portion on a left side or of a right portion on a
right side of said display, to which each of end portions of a
plurality of said common signal lines is connected; a first routing
section made up of a metal film having very low transmittance of
light emitted from a backlight and formed in a manner that a gap
between blocks, being adjacent to each other, formed in a manner so
as to surround said display area, is almost filled in, and wherein
one portion facing said display area of which is connected to said
common wiring; a second routing section made up of said metal film
and formed in a manner that a region surrounded by an outer side
portion of each of said blocks and by a straight line being one
side being orthogonal to one side of said display area along which
said block contacts, being extended toward an end portion of said
glass substrate, is almost filled in, and wherein one portion
facing said display area of which is connected to said common
wiring; and a plurality of common terminals mounted so as to be
adjacent to said signal terminal or said scanning terminal
connected to an end portion of said signal line or said scanning
line making up an outermost portion of each of said blocks and
formed on said first and second routing sections at an end portion
of said glass substrate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a liquid crystal display
(hereinafter referred simply as an LCD) and an image display
device, and more particularly to the LCD used as a monitor or a
like of a computer and provided with liquid crystal cells arranged
in a matrix form and the image display device equipped with the
above LCD.
[0003] The present application claims priority of Japanese Patent
Application No. 2000-241714 filed on Aug. 9, 2000, which is hereby
incorporated by reference.
[0004] 2. Description of the Related Art
[0005] FIG. 10 is a top view of an example of configurations of a
conventional LCD constructed of a transverse electric field-type
liquid crystal which has been disclosed in Japanese Laid-open
Patent Application No. 2001-125122. Here, the transverse electric
field-type liquid crystal refers to a liquid crystal in which an
electric field is formed in a transverse direction (that is, in a
direction parallel to an upper face on an glass substrate 1 being
approximately quadrangular on which the LCD is formed) in a liquid
crystal cell. The transverse electric field-type liquid crystal has
a characteristic of having a small dependency on a viewing angle in
contrast and therefore it is increasingly used in recent years.
[0006] The disclosed LCD is an active-matrix LCD using a TFT (Thin
Film Transistor) as a switching element and, as shown in FIG. 11,
includes a dot pixel portion 4 surrounded by a plurality of
scanning lines 2 disposed at specified intervals in a column
direction (that is, in a longitudinal direction) and a plurality of
signal lines 3 disposed at specified intervals in a row direction
(that is, in a transverse direction), a liquid crystal cell 5
mounted on each of the dot pixel portion 4 having a liquid crystal
layer serving equivalently as a capacitive load, a pixel electrode
6 and a common electrode 8 formed opposite to each other in a
manner that a liquid crystal layer is put between the pixel
electrode 6 and the common electrode 8 and a TFT 7 whose source is
connected to one end of the pixel electrode 6. The LCD in this
example displays characters, images, or a like, while a common
voltage V.sub.com is applied to the common electrode 8 through a
common signal line 9 in each row and in each column, when a data
signal produced based on a video signal is applied to the signal
line 3 and when a scanning signal produced based on a horizontal
sync signal and a vertical sync signal is applied to the scanning
line 2. Each of the common signal lines 9 is connected to a common
wiring 10 which is mounted in a shape of an approximate character
"" (or the approximate character "") (see FIG. 10) in a manner that
it surrounds a display area 11 where the dot pixel portion 4 are
arranged in a matrix form.
[0007] Moreover, though not shown in FIG. 11, more exactly, it can
be considered as if an equivalent capacitors were to be formed by
the liquid crystal layer serving as a dielectric in the liquid
crystal cell 5 and by the pixel electrode 6 and the common
electrode 8 sandwiching the liquid crystal layer in a manner to be
opposite to each other and that other capacitors are further
connected in parallel to the liquid crystal layer of the liquid
crystal cell 5. These other capacitors are called a common storage
in a sense that they are formed relative to the common electrode 8
and called an auxiliary capacitor in a sense that it helps the
liquid crystal layer in the liquid crystal cell 5 to accumulate a
signal charge for one vertical sync period of time.
[0008] In the LCD shown in FIG. 10, all the signal lines 3 are
routed to an upper portion on an upper side of the display area 11
and divided into three blocks 12.sub.1 to 12.sub.3 and a plurality
of signal lines 3 making up each of the blocks 12.sub.1 to 12.sub.3
is gathered in a manner to form an approximately trapezoidal shape
and an end of each of the signal lines 3 is connected to each of
corresponding signal terminals arranged at a predetermined pitch.
Similarly, all the scanning lines 2 are routed both to a right
portion on a right side of the display area 11 and to a left
portion on a left side of the display area 11 and divided into
three blocks 13.sub.1 to 13.sub.3 and 14.sub.1 to 14.sub.3 and a
plurality of scanning lines 2 making up each of the blocks 13.sub.1
to 13.sub.3 and of the blocks 14.sub.1 to 14.sub.3 is gathered in a
manner to form an approximately trapezoidal shape and an end of
each of the scanning lines 2 is connected to each of corresponding
scanning terminals arranged at a predetermined pitch. A pair of the
scanning terminals disposed in a position symmetrical right and
left is connected to each other through the same scanning line
2.
[0009] The common wiring 10, as shown in FIG. 10, is mounted in a
portion adjacent to the display area 11 in a shape of the
approximate character "" (or the approximate character ""). The
common wiring 10 is routed to an upper portion of the glass
substrate 1 along both ends of each of the blocks 12.sub.1to
12.sub.3 in the upper portion on the upper side of the display area
11 to form routing sections 10.sub.a1 to 10.sub.a6. The common
wiring 10 is routed to a leftmost portion of the glass substrate 1
along both ends of each of the blocks 13.sub.1 to 13.sub.3 in the
left portion on the left side of the display area 11 to form the
routing sections 10.sub.b1 to 10.sub.b6. The common wiring 10 is
routed to a rightmost portion of the glass substrate 1 along both
ends of each of the blocks 14.sub.1 to 14.sub.3 in the right
portion on the right side of the display area 11 to form the
routing sections 10.sub.c1 to 10.sub.c6. An end of each of the
routing sections 10.sub.a1 to 10.sub.a6, 10.sub.b1 to 10.sub.b6,
and 10.sub.c1 to 10.sub.c6 is connected to each of corresponding
common terminals 15.sub.1 to 15.sub.6, 16.sub.1 to 16.sub.6, and
17.sub.1 to 17.sub.6 respectively.
[0010] The aim of dividing the scanning lines 2 and signal lines 3
into blocks 12.sub.1 to 12.sub.3, 13.sub.1 to 13.sub.3, and
14.sub.1 to 14.sub.3 each having specified numbers of lines and of
forming each of the routing sections 10.sub.a1 to 10.sub.a6,
10.sub.b1 to 10.sub.b6, and 10.sub.c1 to 10.sub.c6 of the common
wiring 10 along both ends of corresponding blocks 12.sub.1 to
12.sub.3, 13.sub.1 to 13.sub.3, and 14.sub.1 to 14.sub.3 and of
routing the scanning lines 2 and signal lines 3 to form the
approximately trapezoidal shape so that each of the end portions is
connected to each of the scanning terminal and of the signal
terminals and each of common terminals being mounted to be placed
at the specified pitch, is to place each of terminals and end
portions fixedly in a specified position. Also, the aim of placing
each of terminals and end portions fixedly in the specified
position is to enable a package being one of a TCP (Tape Carrier
Package) mounted by using TAB (Tape Automated Bonding) technology
and being used in a driving circuit to drive the LCD to be commonly
used in different kinds of the LCDS. The LCD, while the TCP is
connected, by using a thermo compression bonding method, to the
scanning terminals and signal terminals connected to the blocked
scanning lines 2 and signal lines 3 and common terminals 15.sub.1
to 15.sub.6, 16.sub.1 to 16.sub.6, and 17.sub.1 to 17.sub.6
connected to the common wiring 10, is connected to a driving
circuit mounted on the TCP or a printed board through the TCP. That
is, by arranging each of the terminals and end portions at the
specified pitch being common to various types of the LCD, each of
terminals of the TCP to be connected to these terminals can be
placed in a specified position accordingly and a package for the
driving circuit being the TCP can be used commonly in different
kinds of the LCDs.
[0011] By configuring above, since common terminals 15.sub.1 to
15.sub.6, 16.sub.1 to 16.sub.6, and 17.sub.1 to 17.sub.6 for every
block made up of the scanning lines 2 and signal lines 3 are
provided, wiring resistance of the common wiring 10 can be
dispersed more and can be reduced more, as a whole, compared with a
case in which the common terminal are mounted simply on both ends
in the upper portion on the upper side, in the right portion on the
right side and in the left portion on the left side of the display
area 11 (that is, a case in which, in FIG. 10, only the common
terminals 15.sub.1, 15.sub.6, 16.sub.1, 16.sub.6, 17.sub.1, and
17.sub.6 were to be provided), as a result, crosstalk and/or
dispersion in luminance among the dot pixel portions 4 can be
reduced.
[0012] However, when the above conventional LCD is used as a
monitor for a computer or a like, it presents the following
problems.
[0013] Let it be assumed that an image as shown in FIG. 12 is
displayed on a color LCD called an SXGA (Super Extended Graphics
Array) which can provide a resolution of 1280 pixels.times.1024
pixels. In this color LCD, color filters are arranged in a stripe
manner in which color filters for three primary colors R (red), G
(green), and B (blue) each corresponding to each of the liquid
crystal cell 5 are arranged repeatedly in order of R, G, and B
colors each corresponding to each of the liquid crystal cell 5 in a
row direction and color filters for the same colors are arranged
repeatedly in a column direction, and one pixel is made up of three
dot pixel portions 4 for the R, G, and B colors. Therefore, the
number of dot pixel portions 4 of the LCD of the example is 3840
.times.1024 pixels. Hereinafter, a shape of an image to be
displayed is expressed by the number of the dot pixel portions 4.
In FIG. 12, a central window portion is of a quadrangular shape
made up of 3072.times.256 pixels by which a white color is
displayed, and the background portion surrounding the above window
portion has a width of 384 pixels and formed in a shape of the
character "", which displays a stripe in which a white and a black
color alternately and repeatedly appear for each pixel made up of
three dot pixels portions 4 for the R, G, and B colors. Moreover,
to drive the above color LCD, a dot reverse driving method is
employed in which a data signal whose voltage to be applied to the
pixel electrode 6 is reversed for every dot pixel portion 4
relative to a common voltage V.sub.com being applied to the common
electrode 8, is fed to the signal line 3. The dot reverse driving
method is conventionally used widely for driving the color LCD
because a life of the color LCD is shortened if the voltage of a
same polarity continues to be applied to its liquid crystal cell 5
and because, even if the voltage to be applied to the liquid
crystal cell 5 becomes opposite in polarity, the liquid crystal 5
can maintain all the same transmitted light characteristic.
Moreover, in this color LCD, a so-called normally black mode in
which, in a state of no voltage applied, transmittance of light
through the liquid crystal is low, is employed and, when an
absolute value of a voltage to be applied to the liquid crystal
layers in the three dot pixels portions 4 for R, G, and B colors
making up one pixel is approximately 0 volts, a black color is
displayed while an absolute value of the voltage to be applied to
the liquid crystal layers in the three dot pixels portions 4 for
the R, G, and B colors making up one pixel is approximately 5
volts, a white color is displayed.
[0014] First, to the liquid crystal layer in each of dot pixel
portions 4 connected to the scanning lines 2 which transverses
across a background portion shown in FIG. 12 is applied a data
signal having a voltage shown in FIG. 13A. That is, to the liquid
crystal layer in the dot pixel portions 4 for the R and B colors,
out of the three dot pixels portions 4 for the R, G, and B colors
making up one pixel to display a white color, is applied a voltage
having an absolute value of Vp (in the example, 5 V) which is of
positive polarity relative to the common voltage Vcom and to the
liquid crystal layer in the dot pixel portion 4 for the G color is
applied a voltage having an absolute value of Vp (in the example, 5
V) which is of negative polarity relative to the common voltage
Vcom. On the other hand, to the liquid crystal layer in the dot
pixel portions 4 for the Rand B colors, out of the three dot pixels
portions 4 for the R, G, and B colors making up one pixel to
display a black color, is applied a voltage having an absolute
value of approximately 0 V which is of positive polarity relative
to the common voltage Vcom and to the liquid crystal layer in the
dot pixel portion 4 for the G color is applied a voltage having an
absolute value of approximately 0 V which is of negative polarity
relative to the common voltage Vcom. When the data signal having
voltages shown in FIG. 13A is fed through the signal line 3 to the
liquid crystal layer in each of the dot pixel portions 4, the
common voltage Vcom is changed by a coupling capacitor existing
between each of the signal lines 3 and each of the common signal
line 9 to which the common voltage Vcom is applied. Though the
number of dot pixel portions 4 connected to one scanning line 2 is
made up of 3840 pixels, since the stripe in which the white color
and the black color appears repeatedly for one pixel in the
background portion and the voltage having an absolute value of 0 V
is applied to a half (1920 pixels) of the pixels of the dot pixel
portion 4 displaying the black color, the applied voltage hardly
contributes to the change in the common voltage Vcom. Moreover, out
of the three dot pixels 4 portions 4 for the R, G, and B colors
making up one pixel, though a polarity of the liquid crystal layers
in the dot pixel portion for the R color and the liquid crystal
layer in the dot pixel portion 4 for the G color being adjacent to
each other is different, since the voltage having the same absolute
value Vp (in the example, 5 V) is applied, the change in the common
voltage Vcom is cancelled out. That is, out of the dot pixel
portion 4 made up of 3840 pixels, the dot pixel portion 4
contributing to the change in the common voltage Vcom is the dot
pixel portion 4 for the B color making up the pixel displaying the
white color and the number of pixels making up the dot pixel
portion 4 is 640 pixels as obtained by an equation (1).
3840/(2.times.3)=640 (1)
[0015] Thus, due to an influence of the voltage having an absolute
value 5 V applied to the liquid crystal layer of 640 pixels out of
the 3840 pixels, the common voltage Vcom is changed to be a common
voltage V' com as shown in FIG. 13 (1). Because of this, since same
results occur as if a voltage having an absolute value Vp1 being
smaller than the absolute value of Vp were to be applied to the
liquid crystal layer in the dot pixel portions 4 for the R and B
colors and as if a voltage having an absolute value Vp2 being
larger than the absolute value of Vp were to be applied to the
liquid crystal layer in the dot pixel portion 4 for the G color, a
stripe in greenish color, as a whole, instead of the stripe in the
white and black colors originally expected, is displayed in the
background portion. Moreover, when the color filters for three
colors are arranged in order of the G, R, and B colors, a stripe in
reddish color as a whole is displayed. When the color filters for
three colors are arranged in order of the R, B, and G colors, a
stripe in bluish color as a whole is displayed. Such the phenomenon
is hereinafter called color degradation.
[0016] On the other hand, to the liquid crystal layer in each of
the dot pixel portion 4 connected to the scanning line 2 which
transverses across the window shown in FIG. 12 is applied a data
signal having voltages shown in FIG. 13B. That is, in the
background portion and the window portion, to the liquid crystal
layer in the dot pixel portions 4 for the R and B colors, out of
the three dot pixels portions 4 for the R, G, and B colors making
up one pixel displaying a white color, is applied a voltage having
an absolute value of Vp (in the example, 5 V) which is of positive
polarity relative to the common voltage Vcom and to the liquid
crystal layer in the dot pixel portion 4 for the G color is applied
a voltage having an absolute value of Vp (in the example, 5 V)
which is of negative polarity relative to the common voltage Vcom.
On the other hand, to the liquid crystal layer in the dot pixel
portions 4 for the R and B colors, out of the three dot pixels
portions 4 for the R, G, and B colors making up one pixel to
display the black color, is applied a voltage having an absolute
value of approximate 0 V which is of positive polarity relative to
the common voltage Vcom and to the liquid crystal layer in the dot
pixel portion 4 for the G color is applied a voltage having an
absolute value of approximate 0 V which is of negative polarity
relative to the common voltage Vcom. In this case, when the data
signal having voltages shown in FIG. 13A is applied through the
signal line 2 to the liquid crystal layer in each of the dot pixel
portion 4 connected to the same scanning line 2, though, due to the
coupling capacitor existing between each of the signal lines 3 and
the common signal line 9 to which the common voltage Vcom is
applied, the common voltage Vcom is changed, an amount of the
change is smaller when compared with the case shown in FIG. 13A.
That is, in the dot pixel portion 4 made up of 3072 pixels forming
the window portion, out of the dot pixel portion 4 made up of 3840
pixels, since a voltage having an absolute voltage of Vp (in the
example, 5 V) is applied to the liquid crystal layers in all dot
pixel portions 4, the change in the common voltage Vcom between the
dot pixel portions 4 being adjacent to each other is cancelled out.
In the dot pixel portion 4 made up of 768 pixels (3840 pixels-3072
pixels) forming the background portion, since the same as in the
case shown in FIG. 13A can be applied thereto, the dot pixel
portion 4, out of the dot pixel portion 4 made up of 3840 pixels,
contributing to the change in the common voltage Vcom is the dot
pixel portion 4 for the B color making up the pixel to display the
white color in the dot pixel portion 4 made up of 768 pixels
forming the background portion, the number of the pixels of which
is 128 pixels as obtained by an equation (2).
(3840-3071)/(2.times.3)=128 (2)
[0017] Thus, due to an influence by the voltage having the absolute
value of 5 V applied to the liquid crystal layer in the dot pixel
portion 4 made up of 128 pixels, out of the dot pixel portion 4
made up of 3840 pixels, the common voltage Vcom is changed to the
common voltage V' com as shown in FIG. 13B, however, the change is
smaller when compared with the case shown in FIG. 13A. Therefore,
the color degradation described above is reduced. A phenomenon that
a difference is produced in the color degradation between the dot
pixel portion 4 connected to the scanning line 2 traversing across
the background portion and the dot pixel portion 4 connected to the
scanning line 2 traversing across the window portion is hereinafter
called horizontal stroke. Such the phenomena as the color
degradation or horizontal stroke occur because wiring resistance at
each of the routing sections 10.sub.a1 to 10.sub.a6, 10.sub.b1 to
10.sub.b6, and 10.sub.c1 to 10.sub.c6 is comparatively large, which
causes the common voltage Vcom to be applied to these routing
sections to be readily changed.
[0018] There is a possibility that such the phenomena as the color
degradation and horizontal stroke occur, more or less, even in a TN
(Twisted Nematic)--LCD whose dot pixel portion 4 has configurations
as shown in FIG. 14 and a common storage (in FIG. 14, same
reference numbers are assigned to parts having the same function as
those in FIG. 11 and their descriptions are omitted accordingly).
The reason is that, if configurations of the routing sections
10.sub.a1 to 10.sub.a6, 10.sub.b1 to 10.sub.b6 and 10.sub.c1 to
10.sub.c6 are approximately the same as those shown in FIG. 19, the
resistance at the routing section affects the change in the common
voltage more or less. Moreover, in FIG. 14, the common signal line
9 serves also as the common electrode 8.
[0019] Since each of the routing sections 10.sub.1a to 10.sub.a6,
10.sub.b1 to 10.sub.b6 and 10.sub.c1 to 10.sub.c6 of the common
wiring 10 is formed along both ends of the blocks 12.sub.1 to
12.sub.3, 13.sub.1 to 13.sub.3, and 14.sub.1 to 14.sub.3, light
from a backlight leaks from a clearance between blocks being
adjacent to each other, causing irregularity of luminance at edge
portions surrounding the display area 11. This phenomenon is
hereinafter called luminance irregularity.
SUMMARY OF THE INVENTION
[0020] In view of the above, it is an object of the present
invention to provide an LCD capable of reducing wiring resistance
at routing sections of common wirings and changes in a common
potential to be applied to the common wiring to decrease "color
degradation" and "horizontal stroke" and "luminance irregularity"
and an image display device equipped with the above LCD.
[0021] According to a first aspect of the present invention, there
is provided a liquid crystal display including:
[0022] a liquid crystal cell disposed at each point of
intersections of a plurality of scanning lines, extending in a row
direction, mounted at specified intervals in a display area being
approximately quadrangular in shape placed at a predetermined
position on a glass substrate being approximately quadrangular in
shape and of a plurality of signal lines, extending in a column
direction, mounted at specified intervals and containing a common
electrode;
[0023] signal terminals mounted at either or both of upper end
portions or lower end portions of the glass substrate at a
specified pitch, to which end portions of the signal lines routed
to either or both of an upper portion on an upper side or of a
lower portion on a lower side of the display area and divided into
two or more blocks and gathered are connected;
[0024] scanning terminals mounted at either or both of left end
portions or right end portions of the glass substrate at a
specified pitch, to which end portions of the scanning lines routed
to either or both of a left portion on a left side or of a right
portion on a right side of the display area and divided into two or
more blocks and gathered are connected;
[0025] common signal lines each being mounted in each row and each
column in the display area used to apply a common voltage to the
common electrode;
[0026] common wirings each being mounted at either or both of an
upper portion on an upper side or of a lower portion on a lower
side of the display area and mounted at either or both of a left
portion on a left side or of a right portion on a right side of the
display area, to which each of end portions of a plurality of the
common signal lines is connected;
[0027] a first routing section made up of a metal film having very
low transmittance of light emitted from a backlight and formed in a
manner that a gap between blocks being adjacent to each other along
one side of the display area is almost filled in, and wherein one
portion facing the display area of which is connected to the common
wiring;
[0028] a second routing section made up of the metal film and
formed in a manner that a region surrounded by an outer side
portion of each of the blocks and by straight lines being four side
lines of the display area being extended toward an end portion of
the glass substrate is almost filled in, and wherein the one
portion facing the display area of which is connected to the common
wiring; and
[0029] a plurality of common terminals mounted so as to be adjacent
to the signal terminal or the scanning terminal connected to an end
portion of each of the signal lines or the scanning lines making up
an outermost portion of each of the blocks and formed on the first
routing section and the second routing section at an end portion of
the glass substrate.
[0030] In the foregoing, a preferable mode is one wherein the first
routing section and the second routing section formed at either or
both of the left portion on the left side or of the right portion
on the right side of the display area are formed on a same layer as
a plurality of the scanning lines is formed and connected to the
common wiring through a contact hole and wherein the first section
and the second section formed at either or both of the upper
portion on the upper side or of the lower portion on the lower side
of the display area are formed on a same layer as a plurality of
the signal lines is formed and connected to the common wiring
through the contact hole.
[0031] According to a second aspect of the present invention, there
is provided a liquid crystal display including:
[0032] a liquid crystal cell disposed at each point of
intersections of a plurality of scanning lines, extending in a row
direction, mounted at specified intervals in a display area being
approximately quadrangular in shape placed at a predetermined
position on a glass substrate being approximately quadrangular in
shape and of a plurality of signal lines, extending in a column
direction, mounted at specified interval, and containing a common
electrode;
[0033] signal terminals mounted at either or both of upper end
portions or lower end portions of the glass substrate at a
specified pitch, to which end portions of the signal lines routed
to either or both of an upper portion on an upper side or of a
lower portion on a lower side of the display area and divided into
two or more blocks and gathered are connected;
[0034] scanning terminals mounted at either or both of left end
portions or right end portions of the glass substrate at a
specified pitch, to which ends of the scanning lines routed to
either or both of a left portion on a left side or of a right
portion on a right side of the display area and divided into two or
more blocks and gathered are connected;
[0035] common signal lines each being mounted in each row and each
column in the display area used to apply a common voltage to the
common electrode;
[0036] common wirings each being mounted at either or both of an
upper portion on an upper side or of a lower portion on a lower
side of the display area and mounted at either or both of a left
portion on a left side or of a right portion on a right side of the
display, to which each of end portions of a plurality of the common
signal lines is connected;
[0037] a first routing section made up of a metal film having very
low transmittance of light emitted from a backlight and formed in a
manner that a gap between blocks, being adjacent to each other,
formed in a manner so as to surround the display area, is almost
filled in, and wherein one portion facing the display area of which
is connected to the common wiring;
[0038] a second routing section made up of the metal film and
formed in a manner that a region surrounded by an outer side
portion of each of the blocks and by a straight line being one side
being orthogonal to one side of the display area along which the
block contacts, being extended toward an end portion of the glass
substrate, is almost filled in, and wherein one portion facing the
display area of which is connected to the common wiring; and
[0039] a plurality of common terminals mounted so as to be adjacent
to the signal terminal or the scanning terminal connected to an end
portion of the signal line or the scanning line making up an
outermost portion of each of the blocks and formed on the first and
second routing sections at an end portion of the glass
substrate.
[0040] In the foregoing, a preferable mode is one wherein the first
routing section facing a corner portion of the display area is made
up of a first approximate trapezoidal portion formed on a same
layer as a plurality of the scanning lines is formed and of a
second approximate trapezoidal portion formed on a same layer as a
plurality of the signal lines is formed,
[0041] wherein the first approximate trapezoidal portion is formed
in a manner that it reaches a place being positioned opposite to
the scanning line disposed at an outermost portion of the adjacent
blocks where a straight line connecting an end of each of the
signal terminals mounted at the specified pitch and an end of each
of the scanning terminals on a side of the display area is extended
and where the common wiring is extended,
[0042] wherein the second approximate trapezoidal portion is formed
in a manner that it reaches a place being positioned opposite to
the signal line disposed at an outermost portion of the adjacent
blocks where a straight line connecting an end of each of the
signal terminals mounted at the specified pitch and an end of each
of the scanning terminals on a side of the display area is extended
and where the common wiring is extended, and
[0043] wherein the first approximate trapezoidal portion and the
second approximate trapezoidal portion are connected to each other
at a portion where they are overlapped through contact holes with
specified numbers and at a specified pitch.
[0044] Also, a preferable mode is one wherein each of the common
wirings is made up of a longitudinal line and a horizontal line
contacting sides of the display area and wherein the longitudinal
line is formed on a same layer as a plurality of the signal lines
is formed and the horizontal line is formed on a same layer as a
plurality of the scanning lines is formed and the common wirings
are connected to each other at a region where the longitudinal line
and horizontal line are overlapped through contact holes and
wherein each of the common signal lines is formed on a same layer
as each of a plurality of the scanning lines is formed and
connected to the longitudinal line through contact holes.
[0045] Furthermore, a preferable mode is one wherein the first
routing section the and second routing section are formed in a
manner that each of the routing sections is placed far, by an
interval being equal to a predetermined pitch, from the scanning
lines or the signal lines being positioned at outermost portions of
blocks adjacent to each other.
[0046] According to a third aspect of the present invention, there
is provided an image display device including a liquid crystal
display stated above.
[0047] With the above configurations, there are provided a first
routing section made up of a metal film having very low
transmittance of light emitted from a backlight and formed in a
manner that a gap between blocks being adjacent along one side of a
display area is almost filled in and a second routing section made
up of the above metal film and formed in a manner that a region
surrounded by an outer side portion of a block mounted outside the
display area and by straight lines being four sides of the display
area which have extended toward end portions of a glass substrate
are almost filled in and, therefore, wiring resistance at a routing
section of common wirings can be reduced and changes in common
potential to be applied to the common wirings can be reduced, which
enables "color degradation" and "horizontal stroke" to be decreased
in the LCD. Also, by using the metal film having very low
transmittance of light, "luminance irregularity" can be also
reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] The above and other objects, advantages, and features of the
present invention will be more apparent from the following
description taken in conjunction with the accompanying drawings in
which:
[0049] FIG. 1 is a top view showing configurations of an LCD
according to a first embodiment of the present invention;
[0050] FIG. 2 is an enlarged schematic equivalent circuit of a
portion of the LCD according to the first embodiment of the present
invention;
[0051] FIG. 3 is a top view showing configurations of an LCD
according to a second embodiment of the present invention;
[0052] FIG. 4 is a top view showing a first modified configuration
of the LCD of the present invention;
[0053] FIG. 5 is a top view showing a second modified configuration
of the LCD of the present invention;
[0054] FIG. 6 is a top view showing a third modified configuration
of the LCD of the present invention;
[0055] FIG. 7 is an enlarged schematic equivalent circuit of a
portion of a fourth modified configuration of the LCD of the
present invention;
[0056] FIG. 8 is an enlarged schematic equivalent circuit of a
portion of a fifth modified configuration of the LCD of the present
invention;
[0057] FIG. 9 is a top view showing a sixth modified configuration
of the LCD of the present invention;
[0058] FIG. 10 is a top view of an example of configurations of a
conventional LCD;
[0059] FIG. 11 is an expanded schematic equivalent circuit of a
pixel making up the conventional LCD;
[0060] FIG. 12 is a diagram explaining inconvenient points in the
conventional LCD;
[0061] FIGS. 13A and 13B are diagram explaining inconvenientpoints
in the conventional LCD; and
[0062] FIG. 14 is an expanded schematic equivalent circuit of the
pixel making up the conventional LCD having another
configuration.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0063] Best modes of carrying out the present invention will be
described in further detail using various embodiments with
reference to the accompanying drawings.
[0064] First Embodiment
[0065] FIG. 1 is a top view showing configurations of an LCD
according to a first embodiment of the present invention. FIG. 2 is
an enlarged schematic equivalent circuit of a portion of the LCD
according to the first embodiment of the present invention. The LCD
of the first embodiment is an active-matrix LCD using a TFT as a
switching element. As shown in FIG. 2, on an approximately
quadrangular glass substrate 21 (refer to FIG. 1) are provided a
dot pixel portion 24 surrounded by each of a plurality of scanning
lines 22 mounted at specified intervals in a column direction (in a
longitudinal direction in the figure) and by each of a plurality of
signal lines 23 mounted at specified intervals in a row direction
(in a transverse direction in the figure), a liquid crystal cell 25
mounted for each of the dot pixel portions 24 and having a liquid
crystal layer serving equivalently as a capacitive load, a pixel
electrode (not shown) and a common electrode (not shown) placed in
a manner to be opposite to each other so that they sandwich the
liquid crystal layer of the liquid crystal cell 25 and a TFT 26
whose source is connected to one end of the corresponding pixel
electrode. Moreover, the LCD of the embodiment can be considered as
a capacitor made up of the liquid crystal layer in the liquid
crystal cell 25 being equivalently a dielectric, the pixel
electrode and the common electrode placed in a manner to be
opposite to each other so that they sandwich the liquid crystal
layer, and is connected to the liquid crystal cell 25 in parallel
and made up of common storage 28 used to accumulate a signal charge
for one vertical sync period. In the LCD of the embodiment, in a
state in which a common voltage Vcom is being applied to the common
electrode through a common signal line 27 mounted in each column
and in each row, a data signal produced based on a video signal is
fed to the signal lines 23 and a scanning signal produced based on
a horizontal sync signal and vertical sync signal is applied to the
scanning lines 22, thus causing a character, image, or a like to be
displayed.
[0066] Each of the common signal lines 27 is formed on the same
layer as the scanning lines 22 are formed and is connected through
a contact hole to common wiring 29 (FIG. 1) formed in a shape of an
approximate character "" (or an approximate character "") in a
manner so as to surround an approximately quadrangular display area
30 in which the dot pixel portions 24 are arranged in a matrix form
(refer to FIG. 1). Longitudinal common wirings 29.sub.a and
29.sub.b of the common wiring 29 are formed on the same layer as
the signal lines 23 are formed and a horizontal common wiring
29.sub.c of the common wiring 29 is formed on the same layer as the
scanning line 22 is formed and at regions where the longitudinal
wirings 29.sub.a and 29.sub.b and the horizontal common wiring
29.sub.c are overlapped, the above longitudinal common wirings
29.sub.a and 29.sub.b are connected to each other, thus causing
these wirings to be formed in the shape of the approximate
character "" (or an approximate character "").
[0067] In the LCD shown in FIG. 1, all the signal lines 23 are
routed to an upper portion on an upper side of the display area 30
and divided into three blocks 31.sub.1 to 31.sub.3 and a plurality
of the signal lines 23 making up each of the blocks 3.sub.1 to
31.sub.3 is gathered in a manner to form an approximately
trapezoidal shape and an end of each of the signal lines 23 is
connected to each of corresponding signal terminals (not shown)
arranged at a predetermined pitch. Similarly, all the scanning
lines 22 are routed both to a right portion on a right side of the
display area 30 and to a left portion on a left side of the display
area 30 and divided into three blocks 32.sub.1 to 32.sub.3 and
33.sub.1 to 33.sub.3 and a plurality of scanning lines 22 making up
each of the blocks 32.sub.1 to 32.sub.3 and of the blocks 33.sub.1
to 33.sub.3 is gathered in a manner to form an approximately
trapezoidal shape and an end of each of the scanning lines 22 is
connected to each of corresponding scanning terminals 34 arranged
at a predetermined pitch (see FIG. 2). A pair of the scanning
terminals 34 disposed in a position symmetrical right and left is
connected to each other through the same scanning line 22.
[0068] Moreover, in the left portion on the left side of the
display area 30, routing sections 35.sub.a1 and 35.sub.a2 are
formed between the blocks 32.sub.1 and 32.sub.3 and between the
blocks 32.sub.2 and 32.sub.3 and a routing section 35.sub.b1 is
formed near an upper side of the block 32.sub.1 and routing section
35.sub.b2 is formed near a lower side of the block 32.sub.3. The
routing section 35.sub.a1 is formed in a manner that each of its
upper and lower portions is placed far, by an interval being equal
to a pitch among wirings in a routing section 22a, from the routing
section 22a for the scanning lines 22 being positioned at outermost
places of blocks 32.sub.1 and block 32.sub.2 and in a manner so as
to form an approximate isosceles triangle so that a gap between the
block 32.sub.1 and the block 32.sub.2 is filled in and is
constructed of a metal film having very low transmittance of light
emitted from a backlight. Also, the routing section 35.sub.a2 is
constructed of the metal film described above and formed in a
manner that each of its upper and lower portions is placed far, by
an interval being equal to a pitch among wirings in the routing
section 22a, from the routing section 22a for the scanning lines 22
being positioned at outermost places of blocks 32.sub.1 and block
32.sub.2 and in a manner so as to form an approximate isosceles
triangle so that a gap between the block 32.sub.2 and the block
32.sub.3 is filled in. Each of first vertexes of the routing
section 35.sub.1a and 35.sub.a2 facing the display area 30 is
formed in a manner that the first vertex and the longitudinal
common wiring 29.sub.a formed on the same layer as the signal lines
23 is formed are partially overlapped and, at the overlapped place,
a vertex is partially connected through a contact hole to the
longitudinal common wiring 29.sub.a. Moreover, second and third
vertexes of the routing section 35.sub.a1 and 35.sub.a2 positioned
on a left end side of the glass substrate 21 are connected to
common terminals 36 formed on the same layer on the left side of
the glass substrate 21 as the scanning lines 22 are formed.
[0069] The routing section 35.sub.b1 is constructed of the metal
film described above and formed in a manner that its lower portion
is placed far, by an interval being equal to a pitch among wirings
in the routing section 22a, from the routing section 22a for the
scanning lines 22 being positioned at an outermost place of
adjacent blocks 32.sub.1 and in a manner so as to form an
approximately right triangle so that its upper side reaches a place
where the horizontal common wiring 29.sub.c is extended in a left
direction. The routing section 35.sub.b2 is constructed of the
metal film described above and formed in a manner that its upper
portion is placed far, by an interval being equal to a pitch among
wirings in the routing section 22a, from the routing section 22a
for the scanning lines 22 being positioned at an outermost place of
adjacent blocks 32.sub.3 and in a manner so as to form an
approximately right triangle so that its lower side reaches a place
where a lower end of the display area 30 is extended in a left
direction. A first vertex of the routing section 35.sub.b1 facing
the display area 30 is formed in a manner that the first vertex is
connected to a left end of the horizontal common wiring 29.sub.c
and that the first vertex and the longitudinal common wiring
29.sub.a formed on the same layer as the signal lines 23 is formed
are partially overlapped and, at the overlapped place, the vertex
is partially connected through a contact hole to the longitudinal
common wiring 29.sub.a. A first vertex of the routing section
35.sub.b2 facing the display area 30 is so formed that the first
vertex and the longitudinal common wiring 29.sub.a formed on the
same layer as the signal line 23 is formed are partially overlapped
and, at the overlapped place, the vertex is connected through a
contact hole to a part of the longitudinal common wiring 29.sub.a.
Moreover, each of second vertexes of the routing sections 35.sub.b1
and 35.sub.b2 existing in the left end of the glass substrate 21
and at a place opposite to an outermost portion of the adjacent
block 32.sub.1 or 32.sub.3 is connected to a common terminal 36
formed on the same layer as the scanning lines 22 in the left end
of the glass substrate 21 are formed.
[0070] Similarly, in the right portion on the right side in the
display area 30, routing sections 37.sub.a1 and 37.sub.a2 are
formed, respectively, between the blocks 33.sub.1 and 33.sub.2 and
between the blocks 33.sub.2 and 33.sub.3 on the same layer as the
scanning lines 22 are formed and the routing sections 37.sub.b1 and
37.sub.b2 are formed, respectively, near an upper side of the block
33.sub.1 and near a lower side of the block 33.sub.3. Since shapes
of the routing sections 37.sub.a1, 37.sub.a2, 37.sub.b1, and
37.sub.b2 and their connections with the longitudinal common
wirings 29.sub.a and 29.sub.b, horizontal common wiring 29.sub.c
and the common terminal 36 are almost the same as in the cases of
the routing sections 35.sub.a1, 35.sub.a2, 35.sub.b1, and 35.sub.b2
except that shapes and positions of the both left and right routing
sections are symmetric with respect to a line; therefore their
descriptions are omitted accordingly.
[0071] In the upper portion on the upper side of the display area
30, routing sections 38.sub.a1 and 38.sub.a2 are formed,
respectively, between the blocks 31.sub.1 and 31.sub.2 and between
the blocks 31.sub.2 and 31.sub.3 on the same layer as the signal
lines 23 are formed and routing sections 38.sub.b1 and 38.sub.b2
are formed, respectively, near a left side of the block 33.sub.1
and near a right side of the block 31.sub.3. The routing section
38.sub.a1 is constructed of the metal film described above and
formed in a manner that each of its left and right portions is
placed far, by an interval being equal to a pitch among wirings in
the routing section 23.sub.a (not shown), from the routing section
23.sub.a for the signal lines 23 being positioned at outermost
places of blocks 31.sub.1 and block 31.sub.2 being adjacent to each
other and in a manner so as to form an approximate isosceles
triangle so that a gap between the block 31.sub.1 and the block
31.sub.2 is filled in. The routing section 38.sub.a2 is constructed
of the metal film described above and formed in a manner that each
of its left and right portions is placed far, by an interval being
equal to a pitch among wirings in the routing section 23.sub.a,
from the routing section 23.sub.a for the signal lines 23 being
positioned at outermost places of blocks 31.sub.1 and block
31.sub.2 being adjacent to each other and in a manner so as to form
an approximate isosceles triangle so that a gap between the block
31.sub.1 and the block 31.sub.2 is filled in. Each of first
vertexes of the routing sections 38.sub.a1 and 38.sub.b2 facing the
display area 30 is so formed that the first vertex and the
horizontal common wiring 29.sub.c formed on the same layer as the
scanning line 22 is formed are partially overlapped and, at the
overlapped place, the vertex is connected through a contact hole to
a part of the horizontal common wiring 29.sub.c. Moreover, each of
second and third vertexes of the routing sections 38.sub.a1 and
38.sub.a2 placed on an upper side of the glass substrate 21 is
connected to the common terminal 36 formed on the same layer as the
signal line 23 on an upper end of the glass substrate 21 is
formed.
[0072] The routing section 38.sub.b1 is constructed of the metal
film described above and formed in a manner that its right side
portion is placed far, by an interval being equal to a pitch among
wirings in the routing section 23.sub.a, from the routing section
23.sub.a for the signal lines 23 being positioned at an outermost
place of adjacent blocks 31.sub.1 and in a manner so as to form an
approximately right triangle so that its left side portion reaches
a place where the longitudinal common wiring 29.sub.a is extended
in a upper direction. The routing section 38.sub.b2 is constructed
of the metal film described above and formed in a manner that its
left side portion is placed far, by an interval being equal to a
pitch among wirings in the routing section 23.sub.a from the
routing section 23.sub.a for the signal lines 23 being positioned
at an outermost place of adjacent blocks 31.sub.3 and in a manner
so as to form an approximately right triangle so that its right
side portion reaches a place where the longitudinal common wiring
29.sub.b is extended in a upper direction. A first vertex of the
routing section 38.sub.b1 facing the display area 30 is connected
to an upper end of the longitudinal common wiring 29.sub.a and is
so formed that the vertex and the horizontal common wiring 29.sub.c
formed on the same layer as the scanning line 22 is formed are
partially overlapped and, at the overlapped place, the vertex is
connected through a contact hole partially to the horizontal common
wiring 29.sub.c. A first vertex of the routing section 38.sub.b2
facing the display area 30 is connected to an upper end of the
longitudinal common wiring 29.sub.b and the vertex and the
horizontal common wiring 29.sub.c formed on the same layer as the
scanning line 22 is formed are partially overlapped and, at the
overlapped place, the vertex is connected through a contact hole
partially to the horizontal common wiring 29.sub.c. Moreover, each
of second vertexes of the routing sections 38.sub.b1 and 38.sub.b2
existing in the upper end of the glass substrate 21 and at a place
opposite to an outermost portion of the adjacent block 31.sub.1 or
31.sub.3 is connected to the common terminal 36 formed on the same
layer as the signal lines 23 in the upper end of the glass
substrate 21 are formed.
[0073] The LCD of the embodiment, when the TCP is connected, by a
thermo compression bonding method, to the scanning terminal 34
connected to the scanning lines 22 gathered in a blocked form and
the signal terminal (not shown) connected to the signal lines 23
gathered in a blocked form and the common terminal 36 connected to
the common wiring 29, is connected to a driving circuit mounted on
the TCP or on a printed board through the TCP.
[0074] Thus, according to the LCD of the embodiment, since each of
the routing sections 35.sub.a1, 35.sub.a2, 35.sub.b1, 35.sub.b2,
37.sub.a1, 37.sub.a2, 37.sub.b1, 37.sub.b2, 38.sub.a1, 38.sub.a2,
38.sub.b1, and 38.sub.b2 is constructed of the metal film having
very low transmittance of light emitted from the backlight in a
manner that the gap between blocks is almost filled in or a region
surrounded by side portions of the blocks formed outside the
display area 30 and by straight lines extended from four sides of
the display area 30 is filled in, wiring resistance at the routing
sections 35.sub.a1 or the like can be reduced more when compared
with the case of the conventional LCD. Therefore, even if the LCD
of this embodiment is operated in a normally black mode and the
color filters for the R, G, and B colors are arranged in a stripe
form and an image is displayed by using a dot reverse driving
method, since change in a common potential to be applied to the
common wiring 29 can be reduced more when compared with the case of
the conventional LCD, color degradation or horizontal stroke can be
reduced. Moreover, since the routing sections 35.sub.a1 or the like
are constructed of such metal films having very low transmittance
of light emitted from the backlight, the "luminance irregularity"
occurring at an edge portion surrounding the display area 30 caused
by a leak of light emitted from the backlight from the gap between
adjacent blocks can be reduced.
[0075] Second Embodiment
[0076] FIG. 3 is a top view showing configurations of an LCD
according to a second embodiment of the present invention. In FIG.
3, same reference numbers are assigned to parts or portions having
same functions as those in FIG. 1 or FIG. 2 and their descriptions
are omitted accordingly. In the LCD shown in FIG. 3, instead of
routing sections 35.sub.b1, 37.sub.b1, 38.sub.b1, and 38.sub.b2
provided in FIG. 1, routing sections 41.sub.a and 41.sub.b are
formed.
[0077] The routing section 41.sub.a is made up of a first
approximately trapezoidal portion formed on a same layer as
scanning lines 22 (shown in FIG. 2) are formed and a second
approximately trapezoidal portion formed on a same layer as signal
lines (shown in FIG. 1) 23 are formed.
[0078] The first approximately trapezoidal portion is constructed
of a metal film described above (in the First Embodiment) and
formed in a manner that its lower side portion is placed far, by an
interval being equal to a pitch among wirings in routing section
22.sub.a (shown in FIG. 1), from the routing section 22.sub.a for
the scanning lines 22 being positioned at an outermost place of an
adjacent block 32.sub.1 and in a manner so as to form an
approximate trapezoid so that its upper side portion reaches a
place where a straight line connecting each of lower portions of
signal terminals (not shown) mounted at a specified interval in an
upper portion on an upper side of a display area 30 is extended in
a left direction and its left side portion reaches a place where a
straight line connecting each of right portions of scanning
terminals (not shown) mounted at specified intervals in a left
portion on a left side of the display area 30 is extended in an
upper direction and its right side portion reaches a place where a
longitudinal common wiring 29.sub.a is extended in an upper
direction. On the other hand, the second approximately trapezoidal
portion is constructed of the metal film described above and formed
in a manner so as to form an approximate trapezoid so that its
lower side portion reaches a place where a horizontal common wiring
29.sub.c is extended in a left direction and its upper side portion
reaches a place where a straight line connecting each of lower
portions of signal terminals mounted at a specified interval in the
upper portion on the upper side of the display area 30 is extended
in a left direction and its left side portion reaches a place where
a straight line connecting each of right portions of scanning
terminals mounted at specified intervals in the left portion on the
left side of the display area 30 is extended in an upper direction
and in a manner that its right side portion is placed far, by an
interval being equal to a pitch among wirings in a routing section
23.sub.a (shown in FIG. 1), from the routing section 23.sub.a for
the scanning lines 22 being positioned at an outermost place of an
adjacent block 31.sub.1.
[0079] The routing section 41.sub.a is connected, at an
approximately regular quadrangular portion where the first and
second approximately trapezoidal portions are overlapped, through
contact holes with specified numbers and at a specified pitch, to
the routing section 41.sub.b. A first vertex of the first
approximately trapezoidal portion facing the display area 30 is
connected to a left end portion of the horizontal common wiring
29.sub.c and formed in a manner that the first vertex and the
longitudinal common wiring 29.sub.a formed on the same layer as the
signal lines 23 are formed are partially overlapped and, at the
overlapped portion, the first vertex is partially connected to the
longitudinal common wiring 29.sub.a through a contact hole.
Moreover, a second vertex being disposed on a left end side of a
glass substrate 21 in the above first approximately trapezoidal
portion and being placed opposite to an outermost portion of the
adjacent block 32.sub.1 is connected to a common terminal 36,
disposed on a left side of the glass substrate 21, formed on the
same layer as the scanning lines 22 are formed.
[0080] A first vertex of the second approximately trapezoidal
portion facing the display area 30 is connected to an upper end
portion of the longitudinal common wiring 29.sub.a and formed in a
manner that the above first vertex and the horizontal common wiring
29.sub.c formed on the same layer as the scanning lines 22 are
formed are partially overlapped and, at the overlapped portion, the
first vertex is partially connected to the horizontal common wiring
29.sub.c through a contact hole. Moreover, a second vertex being
disposed on an upper end side of the glass substrate 21 in the
above second approximately trapezoidal portion and being placed
opposite to an outermost portion of the adjacent block 31.sub.1 is
connected to the common terminal 36, disposed on a left side of the
glass substrate 21, formed on the same layer as the signal lines 23
are formed.
[0081] The routing section 41.sub.b is made up of a first
approximately trapezoidal portion formed on the same layer as the
scanning lines 22 are formed and a second approximately trapezoidal
portion formed on the same layer as the signal lines 23 are
formed.
[0082] The first approximately trapezoidal portion is constructed
of the metal film described above and formed in a manner that its
lower side portion is placed far, by an interval being equal to a
pitch among wirings in the routing section 22.sub.a, from the
routing section 22.sub.a for the scanning lines 22 being positioned
at an outermost place of an adjacent block 33.sub.1 and in a manner
so as to form an approximate trapezoid so that its upper side
portion reaches a place where a straight line connecting each of
lower portions of signal terminals mounted at specified intervals
in the upper portion on the upper side of the display area 30 is
extended in a right direction and its right side portion reaches a
place where a straight line connecting each of left portions of
scanning terminals mounted at specified intervals in the right
portion on the right side of the display area 30 is extended in an
upper direction and its left side portion reaches a place where the
longitudinal common wiring 29.sub.b is extended in an upper
direction. On the other hand, the second approximately trapezoidal
portion is constructed of the metal film described above and formed
in a manner so as to form an approximate trapezoid so that its
lower side portion reaches a place where a horizontal common wiring
29.sub.c is extended in a right direction and its upper side
portion reaches a place where a straight line connecting each of
lower portions of signal terminals mounted at specified intervals
in the upper portion on the upper side of the display area 30 is
extended in a right direction and its right side portion reaches a
place where a straight line connecting each of left portions of
scanning terminals mounted at specified intervals in the right
portion on the right side of the display area 30 is extended in an
upper direction and in a manner that its left side portion is
placed far, by an interval being equal to a pitch among wirings in
the routing section 23.sub.a, from the routing section 23.sub.a for
the signal lines 23 being positioned at an outermost place of an
adjacent block 31.sub.3.
[0083] The routing section 41.sub.b is connected at an
approximately regular quadranglar portion where the first and
second approximately trapezoidal portions are overlapped, through
contact holes with specified numbers and at a specified pitch, to
the routing section 41.sub.a. A first vertex of the first
approximately trapezoidal portion facing the display area 30 is
connected to a right end portion of the horizontal common wiring
29.sub.c and formed in a manner that the first vertex and the
longitudinal common wiring 29.sub.b formed on the same layer as the
signal lines 23 are formed are partially overlapped and, at the
overlapped portion, the first vertex is partially connected to the
longitudinal common wiring 29.sub.b through a contact hole.
Moreover, a second vertex being disposed on a right end side of the
glass substrate 21 in the above first approximately trapezoidal
portion and being placed opposite to an outermost portion of the
adjacent block 33.sub.1 is connected to a common terminal 36,
disposed on a right side of the glass substrate 21, formed on the
same layer as the scanning lines 22 are formed.
[0084] A first vertex of the second approximately trapezoidal
portion facing the display area 30 is connected to an upper end
portion of the longitudinal common wiring 29.sub.b and formed in a
manner that the above first vertex and the horizontal common wiring
29.sub.c formed on the same layer as the scanning lines 22 are
formed are partially overlapped and, at the overlapped portion, the
first vertex is partially connected to the horizontal common wiring
29.sub.c through a contact hole. Moreover, a second vertex being
disposed on an upper end side of the glass substrate 21 in the
above second approximately trapezoidal portion and being placed
opposite to an outermost portion of the adjacent block 31.sub.3 is
connected to a common terminal 36, disposed on a upper side of the
glass substrate 21, formed on the same layer as the signal lines 23
are formed.
[0085] The LCD of the second embodiment, when a TCP is connected,
by a thermo-compression bonding method, to a scanning terminal 34
(FIG. 7) connected to the scanning lines 22 gathered in a blocked
form and the signal terminal connected to the signal lines 23
gathered in a blocked form and the common terminal 36 connected to
a common wiring 29, is connected to a driving circuit mounted on
the TCP or on a printed board through the TCP.
[0086] Thus, according to configurations of the LCD of the second
embodiment, since the routing sections 41.sub.a and 41.sub.b made
up of the first approximately trapezoidal portion and the second
approximately trapezoidal portion, respectively, are constructed of
the metal films having very low transmittance of light emitted from
a backlight and formed in a manner that a portion surrounded by the
left side portion of the block 31.sub.1 the upper side portion of
the block 32.sub.1 and a terminal forming region and a portion
surrounded by the right side portion of the block 313, the upper
side portion of the block 33.sub.1 and a terminal forming region
are almost filled in, and since the routing sections 41.sub.a and
41.sub.b are connected at the approximately regular quadrangular
portion where the first and second approximate trapezoidal portions
are overlapped, through contact holes with specified numbers and
mounted at the specified pitch, wiring resistance at the routing
sections 41.sub.1 and 41.sub.b can be reduced more compared with
those at the routing sections 35.sub.b1, 37.sub.b1, 38.sub.b1 and
38.sub.b2 provided in the first embodiment. Therefore, in the
second embodiment, color degradation, horizontal stroke, and
luminance irregularity can be reduced more than in the first
embodiment.
[0087] As described above, according to the embodiments of the
present invention, the wiring resistance at routing sections of the
common wirings can be reduced and the color gradation and
horizontal stroke can be reduced by lowering changes in a common
potential to be applied to the common wiring. Moreover, since the
metal film having very low transmittance of light, the luminance
irregularity can be also reduced.
[0088] It is apparent that the present invention is not limited to
the above embodiments but may be changed and modified without
departing from the scope and spirit of the invention. For example,
in the above embodiments, each of the blocks 31.sub.1 to 31.sub.3,
32.sub.1 to 32.sub.3, and 33.sub.1 to 33.sub.3 is symmetric with
respect with a line and of the approximately trapezoidal shape.
However, their shapes may be changed; for example, in the case of
the LCD with high resolution, since the number of the scanning
lines 22 and signal lines 23 is increased, the shape of the blocks
31.sub.1 to 31.sub.3, 32.sub.1, to 32.sub.3, and 33.sub.1, to
33.sub.3 may be changed depending on the number of the lines, as
shown in FIG. 4 to FIG. 6. Therefore, a shape of the routing
section 35.sub.a1 or the like may be changed in an arbitrary manner
so long as no wiring defects occur between the routing section
35.sub.a1 and the routing section 22.sub.a or the like making up
each of the blocks 31.sub.1, to 31.sub.3, 32.sub.1, to 32.sub.3,
and 33.sub.1, to 33.sub.3 and being disposed opposite to each of
the routing sections 35.sub.a1 or the like (see FIG. 4 to FIG.
8).
[0089] Moreover, in the above embodiments, all scanning lines 22
are routed to the left and right portions on the left and right
sides of the display area 30 and are divided into three blocks on
the left and right sides 32.sub.1 to 32.sub.3 and 33.sub.1, to
33.sub.3, however, in the case of the LCD having the comparatively
small display area 30, as shown in FIG. 9, all the scanning lines
may be routed to either of the left portion on the left side or the
right portion on the right side. The present invention can be
applied to the LCD having such routing and, in this case, forming
of either of the longitudinal common wiring 29.sub.a or 29.sub.b is
not required accordingly.
[0090] Also, in the above embodiments, all the signal lines 23 are
routed to the upper portion on the upper side of the display area
30 and are divided into three blocks 31.sub.1 to 31.sub.3, however,
all the signal lines 23 may be routed to the lower portion on the
lower side of the display area 30 and may be divided into three
blocks. In this case, instead of the horizontal common wiring
29.sub.1, a horizontal line is formed at a place corresponding to a
lower side of the display area 30. Moreover, in the LCD having a
comparatively wider display area, there are cases in which all the
signal lines 23 are routed to both the upper portion on the upper
side and the lower portion on the lower side of the display area 30
and are divided into three blocks on the upper and lower sides, or
the signal lines 23 are divided approximately into two at a center
place, one being for the upper side and the other being for the
lower side and all the signal lines 23 for the upper side are
routed to the upper portion on the upper side of the display area
30 and are divided into three blocks and all the signal lines 23
for the lower side are routed to the lower portion on the lower
side of the display area 30 and are then divided into three blocks.
The present invention can be applied to the LCD having such the
routing. In this case, a horizontal common wiring 29.sub.c is
formed at a place corresponding to a lower side portion of the
display area 30. In any case described above, the shape of the
routing section 35.sub.a1 or the like may be selected depending on
the shape of the block 31.sub.1 or the like, as shown in FIG. 4 to
FIG. 8. Also, the number of the above blocks is not limited to
three and may be set to two, or four, or more.
[0091] Also, in the above embodiments, in the upper portion on the
upper side of the display area 30, the routing sections 38.sub.a1
and 38.sub.a2 are formed on the same layer on which the signal line
23 is formed and is connected through the contact hole to the
horizontal common wiring 29.sub.c formed on the same layer on which
the scanning line 22 is formed. In the left portion on the left
side of and in the right portion on the right side of the display
area 30, the routing section 35.sub.a1, 35.sub.a2, 35.sub.b1,
35.sub.b2, 37.sub.a1, 37.sub.a2, 37.sub.b1, 37.sub.b2, 38.sub.a1,
38.sub.a2, 38.sub.b1, and 38.sub.b2 are formed on the same layer on
which the scanning line 22 is formed and is connected through the
contact hole to the longitudinal common wiring 29.sub.a or 29.sub.b
formed on the same layer on which the signal line 23 is formed.
However, the present invention is not limited to this. For example,
in the upper portion on the upper side of the display area 30, the
routing section is formed on the same layer on which the scanning
line 22 may be formed to be directly connected to the horizontal
common wiring 29.sub.c formed on the same layer on which the
scanning line 22 is formed. In the left portion on the left side of
and in the right portion on the right side of the display area 30,
the routing section is formed on the same layer on which the signal
line 23 may be formed to be directly connected the longitudinal
common wiring 29.sub.a or 29.sub.b formed on the same layer on
which the signal line 23 is formed.
[0092] Moreover, in the above embodiments, the common terminal 36
is connected to any one of the vertex of the routing sections,
however, the common terminal 36 may be connected to any part of
side portions of the routing section on the glass substrate 21 side
or, if possible when the TCP is commonly connected, a wide-shaped
common terminal is used to be connected to an entire side portion
of the routing section on the end side of the glass substrate 21.
As a result, wiring resistance at the routing section can be
reduced more. Also, in the above embodiments, examples are shown in
which the present invention can be applied to the LCD having a
common storage, however, the present invention can be applied to
the LCD having a gate storage. In the above embodiments, a
structure of liquid crystal making up the LCD is not described,
however, the present invention can be applied not only to the LCD
using a transverse electric field-type liquid crystal employed in
the conventional LCD but also to the LCD using a TN (Twisted
Nematic)--type liquid crystal, STN (Super Twisted Nematic)--type
liquid crystal, or a like.
[0093] In addition, in the above embodiments, examples are shown in
which the present invention is applied to an active-matrix LCD
using the TFT as the switching element, however, the present
invention can be applied also to a simple-matrix LCD. When the
present invention is applied to the active-matrix LCD, as the
switching element, not only the TFT but also a MIM (Metal Insulator
Metal) diode, varister, ring diode, MOSFET, or a like can be
employed.
[0094] Moreover, in the above embodiments, whether the LCD is of a
monochrome-type or of a color-type is not described and though the
color degradation and the horizontal stroke are problems associated
with the color LCD, however, the luminance irregularity is also a
problem associated not only with the color LCD but also with a
monochrome LCD. Therefore, the present invention can be applied to
both the monochrome and color LCD. When the present invention is
applied to the color LCD, a color filter used may be of various
types. That is, the color filter may be of a stripe-type, of a
delta-type in which color filters for red, green, and blue colors
each corresponding to each of liquid crystal cells are arranged in
a manner that a position of each of the color filters is deviated
by a half of a pitch from a next scanning line and a dot pixel
portion making up one pixel is arranged in a triangular form, of a
mosaic-type in which the color filters for the red, green, and blue
colors each corresponding to each of the liquid crystal cell are
arranged in a repeated manner by every three color filters in a
scanning direction and in a manner that the position of each of the
color filter is deviated by one or two pitches from a next scanning
line or of a four pixel arrangement-type in which three color
filters for the red, green, and blue colors each corresponding to
each of the liquid crystal cell and any one of the color filters
are arranged in a quadrangular form.
[0095] Moreover, the present invention can be applied not only to
the normally black-type LCD in which, in a state of no voltage
applied, transmittance of light through the liquid crystal is low,
but also to a normally white-type LCD in which, even in a state of
no voltage, transmittance of light through the liquid crystal is
high.
[0096] Furthermore, the LCD of the present invention may be used
for the image display device using the LCD as a monitor of personal
computers or a like.
[0097] It is apparent that the present invention is not limited to
the above embodiments but may be changed and modified without
departing from the scope and spirit of the invention.
* * * * *